Releasable clamp

ABSTRACT

A clamp assembly, including a pair of normally coupled clamp elements for attachment to a unitary workpiece such as a girder of a lattice-type tower, which permits the workpiece to be severed into two adjacent parts at a section between the clamp elements while maintaining the parts in their original relative positions. Subsequent to severance, the adjacent clamp elements may be released relative to each other from a remote position, to permit removal of the separated parts of the workpieces.

mte States Patent 1191 1111 3,863,911 McWilliams Feb. 4, 1975 [5 RELEASABLE CLAMP 2,976,033 3/1961 Martin 269/70 x 2,991,070 7/1961 0vert0n.. 269/43 [75] Inventor- Mcwu'amst NY 3,047,165 7/1962 Hutchinson 269/70 x [73] Assignee: Decair Helicopters, Inc., Spring Valley, NY, Primary ExaminerGranville Y. Custer, Jr. Assistant Examiner-Neil Abrams [22] led: 1973 Attorney, Agent, or Firm-Darby & Darby [21] Appl. No.: 387,733

[57] ABSTRACT 52 us. c1 269/152, 269/37, 269/321 ME, A clamp assembly, i in a P of normally 9911- 403 /12 pled clamp elements for attachment to a unitary work- 51] 1m. (:1 B25b 5/16 piece such as a girder of a lattice-type tower, which 58 Field of Search 269/13, 14, 37, 43, 152, permits the workpiece to be Severed into two adjacent 2 9 70 321 ME, 321 5; 29 200 1 200 J, parts at a section between the clamp elements while 200 p; 403 12 maintaining the parts in their original relative positions. Subsequent to severance, the adjacent clamp el- [56] References i d ements may be released relative to each other from a UNITED STATES PATENTS remote position, to permit removal of the separated 1,225,981 5/1917 Loughridge 269/152 parts of the workp'eces 2,105,954 1/1938 Rippe 269/43 11 Claims, 4 Drawing Figures RELEASABLE CLAMP BACKGROUND OF THE INVENTION This invention relates generally to clamps and, more particularly, to a clamp assembly for gripping a workpiece which is to be severed into two parts and for maintaining the parts in their relative positions after severance.

In various applications, such as in building construction and demolition, it is often necessary to sever an elongate workpiece such as a structural girder at a location somewhere along its length. In these cases it is often desirable to maintain the severed parts of the workpiece in their relative positions rigidly adjacent to each other at least temporarily until it is advantageous to have them released.

One example of such an application is found in the dismantling of lattice-type towers. Lattice-type towers, i.e., towers constructed as a framework of crossed metal members, such as angle girders and cables, are commonly employed to elevate and suspend high tension electrical transmission lines across long distances. Similar structures are used for supporting antennas for broadcasting and receiving. It occasionally become necessary to dismantle these towers when, for example, the transmission line is re-routed or when it is to be eliminated altogether. Such dismantling has, in the past, been ordinarily accomplished by removing from each of the usual four supporting structural girder assemblies spliceplates which connect shorter girders together end-to-end to form each longer girder assembly. The portion of the tower defined by. the girders above these spliceplates is then removed. Succeeding portions of the tower are dismantled in a similar manner.

Thus, of course, the extent of the tower which is dismantled depends upon the location of the spliceplates. It is usually the case that the spliceplates are positioned relatively close to the ground so that the tower portion to be dismantled, i.e. that portion of the tower above the spliceplates, is rather large and so heavy that it must be lowered to the ground upon dismantling. This gives rise to consequent problems of carting it to a new location through what are often densely wooded areas. Ecological problems are often not insignificant inthat trees and foliage may be destroyed in this procedure.

Yet another difficulty inherent in this technique is that once a spliceplate is removed, there is nothing which positively maintains the adjacent girders in posi tion prior to lowering the tower sections to the ground. If the upper tower portion inadvertently slips, the results are potentially catastrophic.

It would be desirable to provide an apparatus which may be connected at any point on the tower which would allow the tower to be severed at that point while maintaining the newly separated adjacent parts in rigid relative position at least temporarily. This would permit these clamps to be located closer to the tower top thereby causing upper tower portions which are created upon severance of the girders to be of a smaller size than was possible previously, thereby allowing removal of individual sections by air, such as by helicopter. It would further eliminate any danger of the upper unclamp the adjacent parts without having to climb up the tower to the clamp location.

SUMMARY OF THE INVENTION Accordingly, one object of this invention is to provide a new and improved clamp for use on a workpiece which is to be severed.

Another object of the invention is to provide a clamp for a workpiece which permits severing the workpiece into parts while rigidly maintaining its severed parts in their relative positions subsequent to severance.

Still another object of the present invention is to provide a clamp which will release the adjacent severed parts ofa workpiece upon command from a remote location.

Briefly, in accordance with a preferred embodiment of this invention, these and other objects are attained by providing a clamp assembly having a pair of clamp members which are individually connectable to the workpiece. While connected to the workpiece, the clamp members are fixed relative to each other so that when the workpiece is severed at a location between the clamp members, the severed workpiece parts are fixed relative to each other through the clamp members. Apparatus is provided which releases the clamp members from their rigid relative position thereby allowing the severed workpiece parts to be separated.

DESCRIPTION OF THE DRAWINGS A more complete appreciation of the invention will be obtained by reference to the following specification in conjunction with the appended drawings where:

FIG. 1 is a partial view of a lattice-type tower having clamp assemblies constructed according to the present invention attached to the vertical supporting girders in a manner to facilitate dismantling of the tower in sections from the top down;

FIG. 2 is a side elevation view of a preferred form of clamp attached to a girder which is shown in partial section;

FIG. 3 is a horizontal sectional view of the clamp taken along line 3-3 of FIG. 2; and I FIG. 4 is a horizontal sectional view of the clamp taken along line 4-4 of FIG. 2.

DESCRIPTION OF TI IE PREFERRED EMBODIMENT Referring now to the drawings wherein like reference characters designate identical or corresponding parts throughout the several views, a lattice-type tower 10 is illustrated in FIG. 1. The tower is typically constructed of four upwardly converging angle members 12 (two not seen) and criss-erossed cables or struts l4. Spliceplates 1% connect lengths of the angle members 12 together, thereby enabling a taller tower to be constructed than might otherwise be possible.

As previously described, in the past when dismantling the tower, the spliceplates 16 were removed and an upper portion A of the tower would be removed. The size of portion A was usually such that it had to be lowered to the ground by a crane and then removed by truck or the like. This was not entirely satisfactory for the reasons already mentioned. It would be desirable to be able to cut up the tower into smaller pieces, removable from the top, as by helicopter, without danger of the pieces falling during the operation.

According to the present invention, a clamp assembly 18 is attached to each angle member 12 substantially nearer the top of the tower thereby defining a tower portion B above the plane of the clamps which is substantially smaller and therefore lighter than the tower portion A. The small tower portion B can easily be removed by helicopter, or other means whereby it would not be necessary to lower it to the ground. As will be seen, the clamp assemblies 18 have the further advantage of maintaining the severed angle members rigidly in their relative positions until the upper tower portion is desired to be removed. This assures that the tower portion B will not inadvertently fall subsequent to severance. However, separation can be attained at will, and from the ground.

Referring to FIG. 2, the clamp assembly 18 is illustrated as connected to angle member 12, prior to that angle member being severed. Clamp assembly 18 includes a pair of clamping members 20, 22.'Each of the clamping members is individually and removably connectable to the angle member 12, and the pair of members are normally mutually interconnected in a rigid manner as described below. It is this mutual interconnection which holds the adjacent parts of the severed workpiece in position. Subsequent to severance, the clamping members may be disconnected from each other thereby disconnecting the adjacent workpiece parts.

Referring to FIGS. 2-4, the first clamping member 20 is illustratively defined by a substantially enclosed sleeve 24 integrally connected, such as by welding, to an upper planar disk 26 having a slot 28 formed partly through it. Sleeve 24 has a right angle cross section (as best seen in FIG. 4) while slot 28 is preferably formed along a diameter of the disk. The relative positions of the disk 26 and sleeve 24 are such that the slot 28 bisects the angle of the sleeve. A pair of set screws 30 threaded in disk 26 open into slot 28. The clamping member 20 is fastened to the tower angle member 12 by inserting a leg of the angle member into slot 28 and then tightening the set screws 30. Thus, it is clear that slot 12 must be wide enough to receive the angle member.

The second clamping member 22 is defined by a lower disk 32 having a radially formed slot 34 similar to and aligned with that formed in first clamping member 20.

Integrally attached to the upper surface of disk 32 is an elongate member 36 having an angular cross section formed by legs 38, 40 (FIG. 4) intersecting at rightangles with each other. The relative positions of the member 36 and slot 34 are the same as in the case of slot 28 and sleeve 24, Le, slot 34 bisects the angle defined by the legs of angle member 36. Set screws 42 cooperate with slot 34 for use in attaching the clamping member 22 to the unitary structural member 12.

The cross section of elongate angle member 36 conforms to the cross sectional shape of the bore defined within sleeve 24 in the first clamping member 20. As will be described below, the angle member 36 is received within the sleeve 24 prior to clamping the assembly to the unitary member 12. It is understood that the cross sections of the sleeve and elongate portion need not be of the precise shape shown, but may comprise other cross sections which will prohibit relative rotation between the elongate portion and the sleeve.

At the upper end of angle member 36, an opening 50 is formed in leg 38. Similarly, an opening 52 is provided in sleeve 24. These openings are provided in corresponding parts of the sleeve and angle member so that upon telescopingly sliding the latter into the former, the openings may be aligned.

Referring to FIG. 2, a bell crank 44 is fastened to the angle member 36 about midway along its length. The bell crank 44 is pivoted about a pivot pin 46 which is associated with a fixed bracket 48. In the embodiment shown, the angle member 36 may be constructed in two parts and the bracket 48 may be welded between the two parts of angle member 36. Of course, the angle member 36 may be a unitary member with the bracket being fastened to it in another manner.

The bell crank 44 is formed with three arms 54, 56 and 58 intersecting at a junction 60 at which the bell crank is pivoted. A compression spring 62 has its ends bearing against the angle member 36 and the end of arm 58 and constantly biases the bell crank in a clockwise direction. A lock pin 69 is pivotally connected to the end of arm 54 so that its end is proximate'to the opening 50 in angle member 36. Finally, a rope 66 or other flexible connector is fastened to the end of arm 56. Upon exerting a pull on the end of rope 66, the bell crank may be rotated in a counterclockwise direction, against the force of spring 62.

The operation of the clamp of the present invention will now be described. Prior to fastening the clamp to a unitary structural member of, for example,.a lattice tower, the angle member 36 of clamping member 22 is inserted into the sleeve 24 of clamping member'20. In order to accomplish a complete insertion, the bell crank must be rotated counterclockwise to remove the pin 69 from opening 50 where it is normally in position due to the biasing of spring 62. Openings 50 and 52 are preferably positioned such that when the upper edge of angle member 36 abuts the'lower surface of disk 26, these openings will be aligned. Upon alignment of these openings, lock pin 69 is allowed to be inserted into the aligned openings. This effectively couples the clamping members 20 and 22 together in a rigid manner. From the above, it is also seen that the slots 28, 34 in the disks 26, 32 are also aligned in the same plane. The coupled clamping members may be attached to the structural member 12 by inserting a leg of member 12 into these slots and then tightening on the set screws 30, 42 until the clamp is rigidly fastened in place. At this point, severance of the structural member may be accomplished by any conventional means, such as by oxiacetylene torch. Dotted lines 68 (FIG. 2) indicate the section at which the structural member 12 may be severed.

Subsequent to severance, the adjacent parts of the structural member, i.e., that part above lines 68 and that part below lines 68, are maintained in adjacent relationship due to the fact that the clamping members 20, 22 are rigidly attached to each other.

When it is desired to allow the adjacent parts of the unitary member to separate, it is only necessary to have an operator on the ground exert tension on line 66. This rotates bell crank 44 in a counterclockwise direction thereby withdrawing locking pin 69 from the aligned openings 50, 52. When this occurs, the clamping members may be easily separated. For example, a helicopter may be coupled onto the upper lattice tower portion and by merely lifting up on it, the two clamping members will slide apart. Of course, the respective clamping members will remain fastened to the structural member and will have to be subsequently removed.

It should be noted that the use of the clamp assembly of the present invention is not limited to the application described herein, i.e., to lattice-type towers, but rather it may be used with any workpiece which is to be severed wherein the parts defined during severance are to be maintained in adjacent relationship.

Of course, numerous variations and modifications of the present invention are possible in light of the above teachings. It is therefore to be understood that the scope of the invention is defined by the appended claims.

I claim:

1. A clamp adapted for attachment to a unitary member which is to be severed to form adjacent separated parts, said clamp being adapted temporarily and detachably to hold said parts in position subsequent to severance, comprising:

a first clamp element attachable to said unitary member on one side of the desired point of severance;

a second clamp element attachable to said unitary member on the other side of said point of severance said second clamp element engaging said first clamp element upon attachment of said elements to the unitary member;

selectively engageable means provided on said first and second clamping elements for rigidly connecting said first clamp element to said second clamp element prior to severance of said unitary member;

and

means provided on one of said clamp elements for disengaging said connecting means thereby disconnecting said first and second clamp elements.

2. A clamp as recited in claim 1 wherein said first clamp elements includes a member having an opening formed therethrough and said second clamp elements includes a second member having an opening formed therethrough, said openings being adapted to be aligned when said first and second clamp members are attached to said member.

3. A clamp as recited in claim 2 wherein said connecting means includes a pin normally biased towards a position located within said aligned openings so that, subsequent to severance, said first and second clamp elements and the adjacent parts to which they are attached are held in position relative to each other by said pin.

4. A clamp as recited in claim 3 wherein said means for disengaging said connecting means includes means for withdrawing said pin from said aligned openings.

5. A clamp as recited in claim 1 wherein said second clamp element includes an elongate portion having a predetermined cross-section and said first clamp element comprises a sleeve having a cross-section of substantially the same shape as said certain cross-section adapted telescopically to receive said elongate portion when clamped to said unitary member.

6. A clamp as recited in claim 5 wherein said elongate portion of said second clamp element has an opening formed therethrough and said sleeve of said first clamp element has an opening formed therethrough, said openings being positioned so that they become aligned when said sleeve receives said elongate portion.

7. A clamp as recited in claim 1 wherein each of said first and second clamp elements has an opening formed therethrough, said openings, upon attachment of said clamp elements to said unitary member, being adapted to be aligned, and wherein. said connecting means include a first arm pivotally connected to said second clamp element, and a pin pivotally connected to a free end of said first arm, said arm being spring biased to a normal position wherein said pin is positioned within said aligned openings.

8. A clamp as recited in claim 7 wherein said means for disengaging said connecting means includes a second arm having one end integrally connected at one end to said first arm and wherein the other end of said second arm is adapted to be urged so as to rotate said first arm against said spring biasing to remove said pin from said aligned openings.

9. A- clamp adapted for attachment to a unitary member which is to be severed to form adjacent separated parts, said clamp being adapted temporarily and detachably to hold said parts in position subsequent to severance, comprising:

first clamping means attachable to said unitary member on one side of the desired point of severance, said first clamping means comprising a hollow member having an angular cross section, a first mounting device fixed to said hollow member and having a slot formed therein for receiving said unitary member to be severed and means for fastening said unitary member within the slot;

second clamping means attachable to said unitary member on the other side of said point of severance;

means provided on said first and second clamping means for releasably coupling said first clamping means to said second clamping means prior to severance and for maintaining said parts in adjacent relationship subsequent to severance; and

means for releasing said couplingmeans thereby uncoupling said first and second clamping means and Y the associated parts of said member.

10. A clamp as recited in claim 9 wherein said second clamping means comprises an angle member having a cross-section which is telescopically receivable within said hollow member, a second mounting device fixed thereto, said second mounting device having a slot formed therein for receiving said unitary member to be severed, and means for fastening said unitary member within said latter slot.

11. A clamp adapted for attachment to an elongate unitary member to facilitate severance and demantling thereof comprising:

an angle member comprising a pair of integral legs,

one of said legs having an opening formed therethrough at an end portion;

a mounting device fixed to said angle member comprising a planar member having a slot formed therein, said slot being positioned to substantially bisect the angle formed by said angle legs;

a bellcrank having a first arm and a second arm joined at an intersection and pivotally secured to said mounting device at said intersection;

a pin pivotally connected at the free end of said first arm in aligned position with said opening, said bellcrank being biased so as to normally urge said pin into said opening and said pin being retractable from said opening upon pivoting said bellcrank;

7 8 a sleeve adapted to receive said angle, said sleeve a mounting device fixed to said angle member and having a pair of legs corresponding to the legs of comprising a planar member having a slot formed said angle member, one of said sleeve legs having therein, said slot being positioned to substantially an opening formed therethrough alignable with the bisect the angle formed by said legs. opening in said angle member; and 

1. A clamp adapted for attachment to a unitary member which is to be severed to form adjacent separated parts, said clamp being adapted temporarily and detachably to hold said parts in position subsequent to severance, comprising: a first clamp element attachable to said unitary member on one side of the desired point of severance; a second clamp element attachable to said unitary member on the other side of said point of severance said second clamp element engaging said first clamp element upon attachment of said elements to the unitary member; selectively engageable means provided on said first and second clamping elements for rigidly connecting said first clamp element to said second clamp element prior to severance of said unitary member; and means provided on one of said clamp elements for diseNgaging said connecting means thereby disconnecting said first and second clamp elements.
 2. A clamp as recited in claim 1 wherein said first clamp elements includes a member having an opening formed therethrough and said second clamp elements includes a second member having an opening formed therethrough, said openings being adapted to be aligned when said first and second clamp members are attached to said member.
 3. A clamp as recited in claim 2 wherein said connecting means includes a pin normally biased towards a position located within said aligned openings so that, subsequent to severance, said first and second clamp elements and the adjacent parts to which they are attached are held in position relative to each other by said pin.
 4. A clamp as recited in claim 3 wherein said means for disengaging said connecting means includes means for withdrawing said pin from said aligned openings.
 5. A clamp as recited in claim 1 wherein said second clamp element includes an elongate portion having a predetermined cross-section and said first clamp element comprises a sleeve having a cross-section of substantially the same shape as said certain cross-section adapted telescopically to receive said elongate portion when clamped to said unitary member.
 6. A clamp as recited in claim 5 wherein said elongate portion of said second clamp element has an opening formed therethrough and said sleeve of said first clamp element has an opening formed therethrough, said openings being positioned so that they become aligned when said sleeve receives said elongate portion.
 7. A clamp as recited in claim 1 wherein each of said first and second clamp elements has an opening formed therethrough, said openings, upon attachment of said clamp elements to said unitary member, being adapted to be aligned, and wherein said connecting means include a first arm pivotally connected to said second clamp element, and a pin pivotally connected to a free end of said first arm, said arm being spring biased to a normal position wherein said pin is positioned within said aligned openings.
 8. A clamp as recited in claim 7 wherein said means for disengaging said connecting means includes a second arm having one end integrally connected at one end to said first arm and wherein the other end of said second arm is adapted to be urged so as to rotate said first arm against said spring biasing to remove said pin from said aligned openings.
 9. A clamp adapted for attachment to a unitary member which is to be severed to form adjacent separated parts, said clamp being adapted temporarily and detachably to hold said parts in position subsequent to severance, comprising: first clamping means attachable to said unitary member on one side of the desired point of severance, said first clamping means comprising a hollow member having an angular cross section, a first mounting device fixed to said hollow member and having a slot formed therein for receiving said unitary member to be severed and means for fastening said unitary member within the slot; second clamping means attachable to said unitary member on the other side of said point of severance; means provided on said first and second clamping means for releasably coupling said first clamping means to said second clamping means prior to severance and for maintaining said parts in adjacent relationship subsequent to severance; and means for releasing said coupling means thereby uncoupling said first and second clamping means and the associated parts of said member.
 10. A clamp as recited in claim 9 wherein said second clamping means comprises an angle member having a cross-section which is telescopically receivable within said hollow member, a second mounting device fixed thereto, said second mounting device having a slot formed therein for receiving said unitary member to be severed, and means for fastening said unitary member within said latter slot.
 11. A clamp adapted for attachment to an elongate unitary member to fAcilitate severance and demantling thereof comprising: an angle member comprising a pair of integral legs, one of said legs having an opening formed therethrough at an end portion; a mounting device fixed to said angle member comprising a planar member having a slot formed therein, said slot being positioned to substantially bisect the angle formed by said angle legs; a bellcrank having a first arm and a second arm joined at an intersection and pivotally secured to said mounting device at said intersection; a pin pivotally connected at the free end of said first arm in aligned position with said opening, said bellcrank being biased so as to normally urge said pin into said opening and said pin being retractable from said opening upon pivoting said bellcrank; a sleeve adapted to receive said angle, said sleeve having a pair of legs corresponding to the legs of said angle member, one of said sleeve legs having an opening formed therethrough alignable with the opening in said angle member; and a mounting device fixed to said angle member and comprising a planar member having a slot formed therein, said slot being positioned to substantially bisect the angle formed by said legs. 